The present invention relates to a valve construction for a "single-shot" valve intended for use in a one time operation. More particularly, the invention relates to a valve which utilizes a deformable metallic bladder and which constitutes an improvement over a previously patented valve construction described and claimed in my U.S. Pat. No. 3,890,994, issued June 24, 1975.
As discussed in my above-identified patent, "single-shot" valves and similar devices operated by pyrotechnic charges and deformable metallic bladders are quite suitable for "one-time" operations in missile systems and the like because they may be stored for long periods of time in an inactive state without severely affecting their reliability and they may be operated from remote locations by means of an electrical firing squib. Furthermore, the fluids which actuate the valves can be confined within the valve and isolated from the primary fluids controlled by the valve. Thus, contamination of the controlled fluids is avoided. While the high pressures generated by the firing squib require certain safety precautions, it has been found that the deformable metallic bladders can be safely designed to contain such pressures during actuation and that the residual pressures assist in holding the bladder in an expanded condition sealing the valve in the closed condition.
Valves utilizing a metallic bladder of the type described are generally characterized by high reliability because they eliminate sliding or rotating seals in the form of O-rings or packing glands which generally permit a limited quantity of leakage and which are always subject to deterioration caused by abrasive wear or hardening. Thus, valve using a deformable, metallic bladder for one-time operation possesses many attractive features militating in favor of its use.
In the normally open valve construction shown in my above referenced patent, the deformable, metallic bladder has a generally tubular shape and has one end in a crushed condition projecting into the fluid passageway through the valve. When the valve is actuated, the crushed portion expands and fills the passageway to obstruct fluid flow through the valve. While such a valve is suitable in many installations, the crushed portion of the bladder does provide some restriction within the fluid passageway prior to actuation of the valve, and also prevents a conventional valve plug from sharing the same seat or portion of the fluid passageway through the valve.
It is, accordingly, a general object of the present invention to provide a valve construction utilizing a deformable, metallic bladder which does not intrude into the fluid passageway through the valve in the normally open valve condition.